Alguersuari and Buemi were replaced by Daniel Ricciardo and Jean-Eric Vergne in December, with Alguersuari a particular surprise following a strong season for the 21-year-old. Horner, however, told the BBC that both drivers had been part of the programme long enough to have been analysed and that retaining them would have halted the opportunity for new young talents to progress.

"Red Bull has invested a huge amount in youth and should be commended," Horner said. "It worked for Sebastian Vettel and provided a genuine opportunity for the talents of Ricciardo and Vergne."

"Both Buemi and Alguersuari had the support of Red Bull to enter F1 and had been supported in Buemi's case for three seasons and in Alguersuari's two and a half seasons, and during that time it enables you to form a picture of how the guys are developing. Obviously a decision was made to elevate both Jean-Eric Vergne and Daniel Ricciardo, who are two of the most exciting talents on the periphery of Formula 1, into race seats at Toro Rosso.

Horner also said that it wasn't just in Formula One that the drivers are being supported, and that the young driver scheme provides them with the opportunity to reach the pinnacle of motorsport by helping them through the lower formulas.

"Red Bull doesn't get the credit it deserves," said Horner. "Neither Buemi nor Alguersuari would have progressed through the junior ranks - let's not forget Alguersuari won the British Formula Three championship - without the support. Red Bull have brought in numerous drivers to F1 now, some who have remained, some who have moved on to other things.

"We have some youngsters on the programme, including a young Scottish lad, Lewis Williamson, who is being supported in the World Series this year and within GP3 last year. He's another driver who wouldn't have the opportunity to progress without the support of the Red Bull junior programme.

"We're in a good position with the Red Bull juniors. When I look around at what other schemes there are, Red Bull has invested a huge amount in youth and should be commended for giving these guys the opportunity that might otherwise have gone missing."